A simple expression for the heat flux between sintered silver powder and 3He-B is derived. The heat flux in the superfluid state is expressed in terms of that in the normal state, without the precise mechanism of heat transfer needing to be specified. A comparison with recent measurements suggests that the energy gap involved is a factor of 0.65 of the bulk value. This implies that the gap is depressed near a boundary and that processes occurring close to the boundary dominate the thermal exchange mechanism.